Valve devices are available in a plurality of embodiments, for example, as multiport valves. In conjunction with an electromagnetic actuation, they are an important component of proportional valve technology. This technology is essentially characterized in that an electrical input signal as voltage is converted into an electrical current with an electronic amplifier of the corresponding voltage level. A proportional solenoid as a switching magnet generates the output quantities force or path proportionally to this electrical current.
These quantities are used as the input signal for the valve device or the hydraulic valve and, correspondingly proportional thereto, for a specific volumetric flow or a specific pressure. For the respective actuated load and a working element that has been actuated with it on a machine, in addition to influencing the direction of movement, the possibility of continuously influencing the speed and force occurs. At the same time, according to a corresponding time characteristic, for example, change of the volumetric flow over time, acceleration or deceleration can be continuously influenced. Depending on the function that is being emphasized, that is, the path function, the flow function, and/or the pressure function, proportional hydraulics is used in directional valves, flow control valves, or so-called pressure valves.
The technical advantages of the proportional valve technology include controlled actuation transitions, continuous control of the setpoints, and the reduction of the hydraulic apparatus for certain control tasks. Furthermore, with proportional valves, prompt and exact sequences of motion are possible with simultaneously improved accuracy of the control processes.
The known valve device solutions still leave something to be desired in the field of proportional valve technology for some control tasks, such as in double-acting hydraulic working cylinders in which the triggering takes place for positioning tasks while avoiding mechanical coupling elements, especially with respect to the operational reliability of the overall system as well as prompt response behavior.
DE 43 19 162 A1 discloses a valve device with two opposing solenoids connected to a valve housing, with fluid connection sites mounted in the valve housing in the form of at least one pump connection P, at least two load or user connections A, B, and at least two tank connections T1 and T2. A valve piston has radial projections that can each be assigned to one fluid connection site A, B, P, T1, T2 at a time in the valve housing. Fluid-conducting paths are between the projections. In a piston neutral position, the path to the respectively assignable user connection A, B is blocked in part or in full, or with the user connections A, B cleared and the respective pump connection P completely blocked by the assignable projection. The known solution relates to a hydraulic valve that can be used for controlling a hydraulic actuator in a roll stabilization system of a motor vehicle. In the known solution, however, possible disturbance variables may adversely affect the hydraulic valve system.
DE 31 19 445 A1 discloses an electrohydraulic control valve with a main housing as a valve housing that surrounds an axial bore in which a valve element as valve piston can be moved. The ends of the valve piston are of a magnetizable material. Solenoid devices are assigned to the housing part as the actuating apparatus on the outer ends of the axial bore to pull the valve element in the direction of one end of the axial bore or the other by excitation of one solenoid device or the other. For compensation of disturbance variables, this known solution has pressure detecting pistons that extend through the valve piston on its two ends. In spite of the possibility of influencing the disturbance variables via the respective pressure detecting piston, this known solution leaves much to be desired with respect to complete compensation for such disturbances.
DE 600 16 510 T2 describes a piloted directional valve with position determination, with a housing that has a number of connections and a piston bore in which each connection discharges. A valve piston is guided to be able to move axially in the piston bore to change the flow paths between the connections. To some extent complex controls for control the valve piston, with the control comprising a piston on each side of the valve piston and one or two pilot valves for setting the valve piston by control of the pilot fluid acting on the pistons. A magnet is attached to one side of the valve piston such that it can be moved in synchronous operation with the valve piston. The magnet is arranged such that it borders at least one site of the valve piston. A magnetic sensor is installed such that it detects the magnetic force of the magnet over the entire displacement path of the valve piston.
The known partially generic valve devices require path sensors and analysis and control electronics. They are thus overall complex in structure, and disturbances in operation are possible.
DE 102 24 739 A1 discloses a valve device of the initially described type. In the known valve device, the pilot valve and the pilot chamber are each located in a control cover located on a side surface of the valve housing. The object of providing a valve control apparatus that requires little installation space in the longitudinal direction of the control valve is achieved here in that the pilot valve and/or the actuator are arranged perpendicular to the longitudinal axis of the control valve in the control cover. The actuator is located on a side surface of the control cover in this case. An adjusting device of the control valve can be on an opposite side surface of the control cover.